1. Field
The invention relates to magnetic shielding device and magnetic shielding method.
2. Related Art
Diagnostic imaging is widely used in medical procedures. Since the diagnostic imaging is a non-invasive procedure, the diagnostic imaging is preferably used for a sensitive organ such as a heart or a brain. Magnetic field source imaging is one example of the diagnostic imaging. These organs generate current caused by activities of neuron. Measurement of the magnetic field caused by the current reflects status of these organs. For example, Magnetocardiogram (MCG), measurement of the magnetic filed generated by a heart, and Magnetoencephalogram (MEG), measurement of the magnetic field generated by a brain, are known.
There are two major problems for measuring these magnetic fields. The first problem relates to a sensitivity of a measuring device. To measure these magnetic fields, a high sensitivity is required. The second problem relates to an external magnetic field. Since an external magnetic field caused by the earth magnetism, for example, is hundred thousands times greater than a magnetic field generated by a living body, a magnetic shielding device to shield the external magnetic field is required.